H1 receptor agonist drugs. What type of drug is olopatadine? Mast cell stabilizer and H1 rec...

H1 receptor agonist drugs.  What type of drug is olopatadine? Mast cell stabilizer and H1 rec...H1 receptor agonist drugs.  What type of drug is olopatadine? Mast cell stabilizer and H1 rec...